A host-based soft device is a hardware device that includes a host software component and a reduced functionality hardware component: respectively a host processor device driver and a “residual” fixed function device. The host processor device driver replaces portions of a fixed function device in a personal computing system (e.g., personal computers, personal digital assistants, etc.). Conventional fixed function devices incorporate one or more dedicated general and special purpose processors (e.g., a microcontroller, a digital signal processor, etc.) and a limited amount of dedicated random access memory (RAM) and read-only memory (ROM). In a host-based soft device, software that executes on one or more dedicated processors is replaced by a host processor device driver that uses main system memory. Typically, a host-based soft device is less expensive than the conventional fixed function devices because the “residual” fixed function device that requires fewer dedicated processors and smaller amounts of dedicated RAM and ROM. In addition, because the host processor is far more powerful than the dedicated processors and has access to more memory, a host-based soft device is often able to use more powerful algorithms, thereby improving performance, increasing efficiency and/or providing higher benchmark scores.
Despite the above advantages of host-based soft devices, their implementation has been limited almost entirely to Microsoft Windows operating systems due to the large market share of Windows family of operating systems, leaving other personal computer operating systems (e.g., BeOS) without available host-based soft devices. In addition, the development of a soft device for Windows has not been an easy process. Recent experience with Windows-based soft devices has shown the inability of Microsoft to develop a stable device driver model. For instance, during the year of 1999, soft modem vendors were simultaneously required to port device software to four different soft modem device drivers for each soft device: specifically, V×D for Windows 98, WDM 1.0 for Windows 98SE, NT for Windows NT 4.0 and WDM 2.0 for Beta releases of Windows 2000. In addition, Windows-based soft devices suffer from excessive latency in the host operating system because Windows operating systems lack real-time quality of service (QoS) guarantees.
Therefore, it would be advantageous to construct a host processor soft device that would be independent of the host processor operating system.